Gatland called Cooper an enigmatic "game-changer" who gives the Wallabies a genuine attacking threat despite his vulnerabilities in defence.

"He's an enigma, isn't he, when he's on form he does things out of the blue, he's got his weaknesses but he puts bums on seats," Gatland said.

"I just think people love to hate him in a certain way but as a rugby player he's absolute quality and he's the kind of player that the game needs, they need someone who does things a little bit different."

Gatland is in Cardiff as Wales head coach but spent Wednesday doing promotional work for next year's British and Irish Lions tour to Australia.

The New Zealander, who just returned to the Welsh camp after a break to focus on the Lions, watched the Wallabies's tests against France and England and said the likes of Cooper, Kurtley Beale, James O'Connor, Will Genia and Digby Ioane - three of whom are injured - were part of Australia's point of difference on a rugby pitch.

"When they're at full strength they do have a real four or five players with real firepower, that attacking threat from all aspects," Gatland said. "For me those players are the real key game-changers, players that can force missed tackles, make breaks, but give you so many attacking options as a No.10 that you've got those threats around you."

Genia and O'Connor missed the spring tour with injury, while Ioane has been starting on the bench while he regains match fitness and form. Beale, playing at five-eighth on the Wallabies's four-test tour of Europe, is the only one of the five who is consistently starting.

Cooper this week announced he would follow in the footsteps of good friend Sonny-Bill Williams and turn to boxing while he weighed up his future.

He is training with the Reds in Brisbane until the end of the year and will spend the next month preparing for a bout in early February.

Gatland seemed bemused with Cooper's strategy but praised his talents as a rugby player despite some of his questionable performances in the gold jersey over the past year.

"When he's good he's very good and when he's bad he can be just as bad as well," he said.

"At times they've tried to hide him defensively and put him at fullback and done different things, but when he's on his game he's world class."

Gatland also likened Cooper's gifts to former Wallabies winger and fullback David Campese.

"He's almost like Campese-esque in a way, a little bit different, bit out there, but incredibly talented and pretty exciting when he's on form."